Active matrix tft array substrate and method of manufacturing the same

Abstract

An active matrix TFT array substrate includes a gate electrode and a gate line formed from a first metal film over a transparent insulating substrate, a gate insulating film to cover the gate electrode and gate line, a semiconductor layer formed over the gate insulating film, a source electrode and a drain electrode formed over the semiconductor layer and a pixel electrode formed from a transparent conductive film. Either of the source or the drain electrode is formed from the transparent conductive film and the active matrix TFT array substrate further comprises a second metal film thereover mainly including one of Al, Cu and Ag.

1 . An active matrix TFT array substrate comprising: 
 a gate electrode and a gate line formed from a first metal film over a transparent insulating substrate;    a gate insulating film to cover the gate electrode and gate line;    a semiconductor layer formed over the gate insulating film;    a source electrode and a drain electrode formed over the semiconductor layer; and    a pixel electrode formed from a transparent conductive film,    wherein either of the source or the drain electrode is formed from the transparent conductive film and further comprises a second metal film thereover mainly including one of Al, Cu and Ag.    
     
     
         2 . The active matrix TFT array substrate according to  claim 1 , wherein the semiconductor layer includes a semiconductor active film and an ohmic contact film.  
     
     
         3 . The active matrix TFT array substrate according to  claim 1 , wherein the source electrode and the drain electrode are formed from the transparent conductive film and further comprises the second metal film thereover.  
     
     
         4 . The active matrix TFT array substrate according to  claim 1 , wherein the transparent conductive film includes at least one of In 2 O 3 , SnO 2  and ZnO.  
     
     
         5 . The active matrix TFT array substrate according to  claim 1 , further comprising a pixel reflective electrode formed from the second metal film.  
     
     
         6 . A liquid crystal display comprising the active matrix TFT array substrate of  claim 1 .  
     
     
         7 . A method of manufacturing an active matrix TFT array substrate comprising: 
 forming a gate electrode and a gate line from a first metal film formed over a transparent insulating substrate by a first photolithography process;    sequentially forming a gate insulating film and a semiconductor layer to cover the gate electrode;    patterning the semiconductor layer by a second photolithography process;    sequentially forming a transparent conductive film and a second metal film mainly including one of Al, Cu or Ag;    forming a resist pattern thinner than other area to at least a part of a pixel electrode, etching the second metal film, the transparent conductive film and an ohmic contact film of the semiconductor layer to form a TFT channel and etching the second metal film exposed by removing the thin resist pattern by a third photolithography process;    forming a passivation film; and    forming a contact hole to the gate insulating film and the passivation film penetrating to a surface of the first metal film and a contact hole to the passivation film penetrating to a surface of the transparent conductive film or the second metal film by a forth photolithography process.    
     
     
         8 . The method according to  claim 7 , wherein the transparent conductive film includes at least one of In 2 O 3 , SnO 2  and ZnO.